Vitamin D receptor gene polymorphisms and the risk of multiple sclerosis: An updated meta-analysis

- TaqI polymorphism in the homozygous model is a significant protective factor for MS.
- For ApaI, MS risk was significantly affected by publication year and race.
- For BsmI, MS risk was significantly influenced by age.
- For FokI, MS risk was markedly affected by publication year.

BackgroundThe association between vitamin D receptor (VDR) gene polymorphisms and multiple sclerosis (MS) has been extensively studied, but results were controversial.MethodsThis meta-analysis aimed to confirm whether VDR gene polymorphisms were associated with MS. Meta-analysis on the association between MS and VDR ApaI, BsmI, TaqI and FokI polymorphisms were conducted using allelic contrast, recessive, homozygotes and dominant models. Data were extracted by standardized forms and odds ratios (OR) with 95% confidence intervals (CI) were calculated using the random effects model if the results were heterogeneous. Stratification analysis by the selected study characteristics were performed to detect potential source of heterogeneity.ResultsA total of 21 relevant studies involving 3593 MS patients and 3917 controls were included in the analysis. The association between TaqI polymorphism and MS risk was significant in the homozygous model (p = 0.006) indicated a significant protective effect of TT TaqI genotype. High latitude (40.1-50°N) was also found markedly influenced TaqI polymorphism and MS risk in the recessive and homozygous models (p = 0.045 and p = 0.015, respectively). Additionally, Asian or low latitude (20.1-30°N) people with ApaI homozygous genotype, '> 2013' publication year people in the allele contrast and dominant models of FokI, '> 40 years' age people with BsmI recessive model also indirectly significantly affected the association between VDR gene polymorphisms and MS risk.ConclusionTaqI polymorphism is a significant protective factor for MS. However, the associations between ApaI, FokI and BsmI polymorphisms and MS were found only by study characteristics.